Morahan has represented the Queensland U-16, Qld Schools and Australia A Schools before entering the Premier Colts (U19) ranks in 2008. He was also one of the top try scorers in the premier competition with 10 tries. He has also represented Australia internationally in the IRB Sevens World Series circuit. He made his 7's debut in the 2008 South Africa Sevens where he was the equal top try scorer with seven tries. He notched up 4 tries in the Wellington leg and his impressive appearance continued when he notched a further 6 tries in San Diego, before joining the Reds academy. He got called up for the Reds making his debut against the Lions in the Super 14 competition before a shoulder injury ruled him out of the season, however Wallaby coach Robbie Deans was sufficiently impressed with the youngster's performances and after a calf injury ruled out Wallaby centre, Stirling Mortlock, Morahan was called up to join the Wallabies on their 2009 Autumn Internationals.
He joined the Australian sevens team for the 2010 Commonwealth Games where his team won the silver medal. He got another call-up from the Wallabies as he was included in their squad for the 2010 Autumn Internationals. Morahan was called up to the Wallabies squad to play the British and Irish Lions following his try against the Lions with the Queensland Reds.
On 20 March 2017, Morahan would leave Australia to travel to England to sign for Bristol Rugby ahead of the 2017-18 season.